Pretreatment of cellulose



UNITED STATES PATENT OFFIQE- PRETREATMENT OF CELLULO SE Coleman R. Caryl, Riverside, Conn, assignor to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application June 27, 1939,

Serial No. 281,325

3 Claims. (01. 260-229) This invention relates touthe esterification of may be used in similar manner, such as ethyl cellulose, as in the preparation of cellulose nilactic acid, isopropyl lactic acid and the like. trate, cellulose acetate, cellulose p-ropionate, cel- The invention will be illustrated in greater delulose butyrate and. the like. More particularly, tail by the following specific example. It should the invention relates to the pretreatment of be understood, however, that this example is 5' cellulose such as cotton linters in order to loosen given primarily for purposes of illustration and the fibres thereof in advance of its esterification. that the invention in its broader aspects is not The esterification of cellulose is remarkably limited thereto. facilitated when the fibres thereof have been Example treated 1 m' of l part of cotton linters is stirred into an aque hydroxy isobutyric acid. This pretreatment 1s Gus solution f alpha hydroxy isobutyric acid preferably carried out at elevated temperatures of 9 strength which has, been heatedto C. of fill-120 Periods 0f 1 t0 3 hours, The stirring is continued for 2 hours while the ing on the type o 08 1 058 a the type of temperature of the solution is maintained at sequent esterification to which it is to be sub- 30-90 Q The sohmon is th drained away jected. from the fibre which is washed with water, dried,

For most P11 9 as in the p p o o and esterified in the usual manner. Cellulose cellulose nitrate and cellulose acetate, a prepretreated in this manner can be esterified with treatment with an 80% aqueous solution of alpha smaller quantities of acetic acid and acetic anhydrox'y isobutyric acid at till-100 C. for 2 hours hydride and in less time than is required for the is satisfa tory esterification of untreated cellulose.

Upon completion of the pretreatment with the What I Claim is: alpha hydroxy isobutyric acid solutionthe excess A of Pretreatmg 7811111958 m advance acid is preferably Separated from the fibre by $11 esterification thereof which comprises centrifuging and washing after which the fibre mg 1t i l i aqueous 01mm of r is dried. It isthen subjected to the usual esterialpha hydroxy lsobutync for t 2 hours fication process for example with acetic acid A method of pretreatmg cellulose madvance of the esterification thereof which comprises and acetw anhydnd? m the usual mrnmn heating it with a. concentrated aqueous solution In some as m.the P of ceuu' of alpha hydroxy isobutyric acid for about 2 hours 0 lose esters of higher aliphatic acids such as buat temperatures of 804W C. tyric or propionic acids, chlorinated alph 3. Amethod of preparing cellulose esters which droxy isobltyric acids m be used to advantagecomprises pretreating .cellulose with a hot con- These acids are Obtained by reacting the corre' centrated aqueous solution of alpha hydroxy isospend chloracetones. s s monoor butyric acid, removing the pretreating solution, 35 Chloracetone, W y y ic a f011QWed by and subjecting the resulting pretreated cellulose hydrolysis t0 the carboxylic i similarly, to the action of an esterification agent. higher homologs of alpha hydroxy isobutyric acid COLEMAN R. CARYL. 

